using System;

namespace PWEmu.ZLib
{
    /// <summary>
    /// 
    /// </summary>
    sealed class InfBlocks
    {
        private const int MANY = 1440;

        // And'ing with mask[n] masks the lower n bits		
        private static readonly int[] inflate_mask = new int[] { 0x00000000, 0x00000001, 0x00000003, 0x00000007, 0x0000000f, 0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff };

        // Table for deflate from PKZIP's appnote.txt.		
        internal static readonly int[] border = new int[] { 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };

        private const int TYPE = 0; // get type bits (3, including end bit)
        private const int LENS = 1; // get lengths for stored
        private const int STORED = 2; // processing stored block
        private const int TABLE = 3; // get table lengths
        private const int BTREE = 4; // get bit lengths tree for a dynamic block
        private const int DTREE = 5; // get length, distance trees for a dynamic block
        private const int CODES = 6; // processing fixed or dynamic block
        private const int DRY = 7; // output remaining window bytes
        private const int DONE = 8; // finished last block, done
        private const int BAD = 9; // ot a data error--stuck here

        internal int mode; // current inflate_block mode 

        internal int left; // if STORED, bytes left to copy 

        internal int table; // table lengths (14 bits) 
        internal int index; // index into blens (or border) 
        internal int[] blens; // bit lengths of codes 
        internal int[] bb = new int[1]; // bit length tree depth 
        internal int[] tb = new int[1]; // bit length decoding tree 

        internal InfCodes codes; // if CODES, current state 

        internal int last; // true if this block is the last block 

        // mode independent information 
        internal int bitk; // bits in bit buffer 
        internal int bitb; // bit buffer 
        internal int[] hufts; // single malloc for tree space 
        internal byte[] window; // sliding window 
        internal int end; // one byte after sliding window 
        internal int read; // window read pointer 
        internal int write; // window write pointer 
        internal System.Object checkfn; // check function 
        internal long check; // check on output 

        internal InfBlocks(ZStream z, System.Object checkfn, int w)
        {
            hufts = new int[MANY * 3];
            window = new byte[w];
            end = w;
            this.checkfn = checkfn;
            mode = TYPE;
            reset(z, null);
        }

        internal void reset(ZStream z, long[] c)
        {
            if (c != null)
                c[0] = check;
            if (mode == BTREE || mode == DTREE)
            {
                blens = null;
            }
            if (mode == CODES)
            {
                codes.free(z);
            }
            mode = TYPE;
            bitk = 0;
            bitb = 0;
            read = write = 0;

            if (checkfn != null)
                z.adler = check = z._adler.Calculate(0L, null, 0, 0);
        }

        internal int proc(ZStream z, int r)
        {
            int t; // temporary storage
            int b; // bit buffer
            int k; // bits in bit buffer
            int p; // input data pointer
            int n; // bytes available there
            int q; // output window write pointer
            int m; // bytes to end of window or read pointer

            // copy input/output information to locals (UPDATE macro restores)
            {
                p = z.nextInIndex; n = z.availableIn; b = bitb; k = bitk;
            }
            {
                q = write; m = (int)(q < read ? read - q - 1 : end - q);
            }

            // process input based on current state
            while (true)
            {
                switch (mode)
                {

                    case TYPE:

                        while (k < (3))
                        {
                            if (n != 0)
                            {
                                r = ZLibConst.Status.Z_OK;
                            }
                            else
                            {
                                bitb = b; bitk = k;
                                z.availableIn = n;
                                z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                                write = q;
                                return inflate_flush(z, r);
                            }
                            ;
                            n--;
                            b |= (z.nextIn[p++] & 0xff) << k;
                            k += 8;
                        }
                        t = (int)(b & 7);
                        last = t & 1;

                        switch (SupportClass.URShift(t, 1))
                        {

                            case 0:  // stored 
                                {
                                    b = SupportClass.URShift(b, (3)); k -= (3);
                                }
                                t = k & 7; // go to byte boundary
                                {
                                    b = SupportClass.URShift(b, (t)); k -= (t);
                                }
                                mode = LENS; // get length of stored block
                                break;

                            case 1:  // fixed
                                {
                                    int[] bl = new int[1];
                                    int[] bd = new int[1];
                                    int[][] tl = new int[1][];
                                    int[][] td = new int[1][];

                                    InfTree.InflateTreesFixed(bl, bd, tl, td, z);
                                    codes = new InfCodes(bl[0], bd[0], tl[0], td[0], z);
                                }
                                {
                                    b = SupportClass.URShift(b, (3)); k -= (3);
                                }

                                mode = CODES;
                                break;

                            case 2:  // dynamic
                                {
                                    b = SupportClass.URShift(b, (3)); k -= (3);
                                }

                                mode = TABLE;
                                break;

                            case 3:  // illegal
                                {
                                    b = SupportClass.URShift(b, (3)); k -= (3);
                                }
                                mode = BAD;
                                z.message = "invalid block type";
                                r = ZLibConst.Status.Z_DATA_ERROR;

                                bitb = b; bitk = k;
                                z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                                write = q;
                                return inflate_flush(z, r);
                        }
                        break;

                    case LENS:

                        while (k < (32))
                        {
                            if (n != 0)
                            {
                                r = ZLibConst.Status.Z_OK;
                            }
                            else
                            {
                                bitb = b; bitk = k;
                                z.availableIn = n;
                                z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                                write = q;
                                return inflate_flush(z, r);
                            }
                            ;
                            n--;
                            b |= (z.nextIn[p++] & 0xff) << k;
                            k += 8;
                        }

                        if (((SupportClass.URShift((~b), 16)) & 0xffff) != (b & 0xffff))
                        {
                            mode = BAD;
                            z.message = "invalid stored block lengths";
                            r = ZLibConst.Status.Z_DATA_ERROR;

                            bitb = b; bitk = k;
                            z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                            write = q;
                            return inflate_flush(z, r);
                        }
                        left = (b & 0xffff);
                        b = k = 0; // dump bits
                        mode = left != 0 ? STORED : (last != 0 ? DRY : TYPE);
                        break;

                    case STORED:
                        if (n == 0)
                        {
                            bitb = b; bitk = k;
                            z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                            write = q;
                            return inflate_flush(z, r);
                        }

                        if (m == 0)
                        {
                            if (q == end && read != 0)
                            {
                                q = 0; m = (int)(q < read ? read - q - 1 : end - q);
                            }
                            if (m == 0)
                            {
                                write = q;
                                r = inflate_flush(z, r);
                                q = write; m = (int)(q < read ? read - q - 1 : end - q);
                                if (q == end && read != 0)
                                {
                                    q = 0; m = (int)(q < read ? read - q - 1 : end - q);
                                }
                                if (m == 0)
                                {
                                    bitb = b; bitk = k;
                                    z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                                    write = q;
                                    return inflate_flush(z, r);
                                }
                            }
                        }
                        r = ZLibConst.Status.Z_OK;

                        t = left;
                        if (t > n)
                            t = n;
                        if (t > m)
                            t = m;
                        Array.Copy(z.nextIn, p, window, q, t);
                        p += t; n -= t;
                        q += t; m -= t;
                        if ((left -= t) != 0)
                            break;
                        mode = last != 0 ? DRY : TYPE;
                        break;

                    case TABLE:

                        while (k < (14))
                        {
                            if (n != 0)
                            {
                                r = ZLibConst.Status.Z_OK;
                            }
                            else
                            {
                                bitb = b; bitk = k;
                                z.availableIn = n;
                                z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                                write = q;
                                return inflate_flush(z, r);
                            }
                            ;
                            n--;
                            b |= (z.nextIn[p++] & 0xff) << k;
                            k += 8;
                        }

                        table = t = (b & 0x3fff);
                        if ((t & 0x1f) > 29 || ((t >> 5) & 0x1f) > 29)
                        {
                            mode = BAD;
                            z.message = "too many length or distance symbols";
                            r = ZLibConst.Status.Z_DATA_ERROR;

                            bitb = b; bitk = k;
                            z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                            write = q;
                            return inflate_flush(z, r);
                        }
                        t = 258 + (t & 0x1f) + ((t >> 5) & 0x1f);
                        blens = new int[t];
                        {
                            b = SupportClass.URShift(b, (14)); k -= (14);
                        }

                        index = 0;
                        mode = BTREE;
                        goto case BTREE;

                    case BTREE:
                        while (index < 4 + (SupportClass.URShift(table, 10)))
                        {
                            while (k < (3))
                            {
                                if (n != 0)
                                {
                                    r = ZLibConst.Status.Z_OK;
                                }
                                else
                                {
                                    bitb = b; bitk = k;
                                    z.availableIn = n;
                                    z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                                    write = q;
                                    return inflate_flush(z, r);
                                }
                                ;
                                n--;
                                b |= (z.nextIn[p++] & 0xff) << k;
                                k += 8;
                            }

                            blens[border[index++]] = b & 7;

                            {
                                b = SupportClass.URShift(b, (3)); k -= (3);
                            }
                        }

                        while (index < 19)
                        {
                            blens[border[index++]] = 0;
                        }

                        bb[0] = 7;
                        t = InfTree.InflateTreesBits(blens, bb, tb, hufts, z);
                        if (t != ZLibConst.Status.Z_OK)
                        {
                            r = t;
                            if (r == ZLibConst.Status.Z_DATA_ERROR)
                            {
                                blens = null;
                                mode = BAD;
                            }

                            bitb = b; bitk = k;
                            z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                            write = q;
                            return inflate_flush(z, r);
                        }

                        index = 0;
                        mode = DTREE;
                        goto case DTREE;

                    case DTREE:
                        while (true)
                        {
                            t = table;
                            if (!(index < 258 + (t & 0x1f) + ((t >> 5) & 0x1f)))
                            {
                                break;
                            }


                            int i, j, c;

                            t = bb[0];

                            while (k < (t))
                            {
                                if (n != 0)
                                {
                                    r = ZLibConst.Status.Z_OK;
                                }
                                else
                                {
                                    bitb = b; bitk = k;
                                    z.availableIn = n;
                                    z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                                    write = q;
                                    return inflate_flush(z, r);
                                }
                                ;
                                n--;
                                b |= (z.nextIn[p++] & 0xff) << k;
                                k += 8;
                            }

                            if (tb[0] == -1)
                            {
                                //System.err.println("null...");
                            }

                            t = hufts[(tb[0] + (b & inflate_mask[t])) * 3 + 1];
                            c = hufts[(tb[0] + (b & inflate_mask[t])) * 3 + 2];

                            if (c < 16)
                            {
                                b = SupportClass.URShift(b, (t)); k -= (t);
                                blens[index++] = c;
                            }
                            else
                            {
                                // c == 16..18
                                i = c == 18 ? 7 : c - 14;
                                j = c == 18 ? 11 : 3;

                                while (k < (t + i))
                                {
                                    if (n != 0)
                                    {
                                        r = ZLibConst.Status.Z_OK;
                                    }
                                    else
                                    {
                                        bitb = b; bitk = k;
                                        z.availableIn = n;
                                        z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                                        write = q;
                                        return inflate_flush(z, r);
                                    }
                                    ;
                                    n--;
                                    b |= (z.nextIn[p++] & 0xff) << k;
                                    k += 8;
                                }

                                b = SupportClass.URShift(b, (t)); k -= (t);

                                j += (b & inflate_mask[i]);

                                b = SupportClass.URShift(b, (i)); k -= (i);

                                i = index;
                                t = table;
                                if (i + j > 258 + (t & 0x1f) + ((t >> 5) & 0x1f) || (c == 16 && i < 1))
                                {
                                    blens = null;
                                    mode = BAD;
                                    z.message = "invalid bit length repeat";
                                    r = ZLibConst.Status.Z_DATA_ERROR;

                                    bitb = b; bitk = k;
                                    z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                                    write = q;
                                    return inflate_flush(z, r);
                                }

                                c = c == 16 ? blens[i - 1] : 0;
                                do
                                {
                                    blens[i++] = c;
                                }
                                while (--j != 0);
                                index = i;
                            }
                        }

                        tb[0] = -1;
                        {
                            int[] bl = new int[1];
                            int[] bd = new int[1];
                            int[] tl = new int[1];
                            int[] td = new int[1];


                            bl[0] = 9; // must be <= 9 for lookahead assumptions
                            bd[0] = 6; // must be <= 9 for lookahead assumptions
                            t = table;
                            t = InfTree.InflateTreesDynamic(257 + (t & 0x1f), 1 + ((t >> 5) & 0x1f), blens, bl, bd, tl, td, hufts, z);
                            if (t != ZLibConst.Status.Z_OK)
                            {
                                if (t == ZLibConst.Status.Z_DATA_ERROR)
                                {
                                    blens = null;
                                    mode = BAD;
                                }
                                r = t;

                                bitb = b; bitk = k;
                                z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                                write = q;
                                return inflate_flush(z, r);
                            }

                            codes = new InfCodes(bl[0], bd[0], hufts, tl[0], hufts, td[0], z);
                        }
                        blens = null;
                        mode = CODES;
                        goto case CODES;

                    case CODES:
                        bitb = b; bitk = k;
                        z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                        write = q;

                        if ((r = codes.proc(this, z, r)) != ZLibConst.Status.Z_STREAM_END)
                        {
                            return inflate_flush(z, r);
                        }
                        r = ZLibConst.Status.Z_OK;
                        codes.free(z);

                        p = z.nextInIndex; n = z.availableIn; b = bitb; k = bitk;
                        q = write; m = (int)(q < read ? read - q - 1 : end - q);

                        if (last == 0)
                        {
                            mode = TYPE;
                            break;
                        }
                        mode = DRY;
                        goto case DRY;

                    case DRY:
                        write = q;
                        r = inflate_flush(z, r);
                        q = write; m = (int)(q < read ? read - q - 1 : end - q);
                        if (read != write)
                        {
                            bitb = b; bitk = k;
                            z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                            write = q;
                            return inflate_flush(z, r);
                        }
                        mode = DONE;
                        goto case DONE;

                    case DONE:
                        r = ZLibConst.Status.Z_STREAM_END;

                        bitb = b; bitk = k;
                        z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                        write = q;
                        return inflate_flush(z, r);

                    case BAD:
                        r = ZLibConst.Status.Z_DATA_ERROR;

                        bitb = b; bitk = k;
                        z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                        write = q;
                        return inflate_flush(z, r);


                    default:
                        r = ZLibConst.Status.Z_STREAM_ERROR;

                        bitb = b; bitk = k;
                        z.availableIn = n; z.totalIn += p - z.nextInIndex; z.nextInIndex = p;
                        write = q;
                        return inflate_flush(z, r);

                }
            }
        }

        internal void free(ZStream z)
        {
            reset(z, null);
            window = null;
            hufts = null;
            //ZFREE(z, s);
        }

        internal void set_dictionary(byte[] d, int start, int n)
        {
            Array.Copy(d, start, window, 0, n);
            read = write = n;
        }

        // Returns true if inflate is currently at the end of a block generated
        // by Z_SYNC_FLUSH or Z_FULL_FLUSH. 
        internal int sync_point()
        {
            return mode == LENS ? 1 : 0;
        }

        // copy as much as possible from the sliding window to the output area
        internal int inflate_flush(ZStream z, int r)
        {
            int n;
            int p;
            int q;

            // local copies of source and destination pointers
            p = z.nextOutIndex;
            q = read;

            // compute number of bytes to copy as far as end of window
            n = (int)((q <= write ? write : end) - q);
            if (n > z.availableOut)
                n = z.availableOut;
            if (n != 0 && r == ZLibConst.Status.Z_BUF_ERROR)
                r = ZLibConst.Status.Z_OK;

            // update counters
            z.availableOut -= n;
            z.totalOut += n;

            // update check information
            if (checkfn != null)
                z.adler = check = z._adler.Calculate(check, window, q, n);

            // copy as far as end of window
            Array.Copy(window, q, z.nextOut, p, n);
            p += n;
            q += n;

            // see if more to copy at beginning of window
            if (q == end)
            {
                // wrap pointers
                q = 0;
                if (write == end)
                    write = 0;

                // compute bytes to copy
                n = write - q;
                if (n > z.availableOut)
                    n = z.availableOut;
                if (n != 0 && r == ZLibConst.Status.Z_BUF_ERROR)
                    r = ZLibConst.Status.Z_OK;

                // update counters
                z.availableOut -= n;
                z.totalOut += n;

                // update check information
                if (checkfn != null)
                    z.adler = check = z._adler.Calculate(check, window, q, n);

                // copy
                Array.Copy(window, q, z.nextOut, p, n);
                p += n;
                q += n;
            }

            // update pointers
            z.nextOutIndex = p;
            read = q;

            // done
            return r;
        }
    }
}